@Brandon Mattingly No problem, sir!
Regarding vacancy, you would start with your lease term (1 year), then add your estimated turnover time (repairs/cleaning, interviewing new tenants). Ideally, this is 2-3 weeks, but "ideal" in this business often feels mythical :) For reference, 1BR apartment complex owners use 5% vac rate in this scenario.
You should never assume your first tenant or anyone thereafter will stay longer than their original commitment. So count on an annual turnover rate. My first property was a single family, and my first tenant broke their lease; left after 7 months. When the whole dream of SF is to find someone to stay for 10 years, this didn't feel great. This is where the vacancy rates helped protect me. Try not to make margins so thin that they don't reflect the real world. It could be 4 tenants before you find a solid long term renter. And that's ok.
Just a couple reasons why I recommend using 8% vac For SF in our region. That gives you an extra 10 days above the small apartment vac rate to handle any extra hurdles with a larger property and a smaller tenant pool. Hope that helps!